
<html>

<table width=100%><tr>
    <td align=left><a href="updates_shmem.html">&lt;- Dynamic Updates using Shared Memory</a></td>
    <td align=right> &nbsp; </td>
</tr></table>
<hr>
<h2>Dynamic Updates Using the GUI</h2>

  <p>
  Lastly, a simple Graphical User Interface (GUI) is provided, compiled with 
  FLTK for simplicity and platform independence.  The GUI uses a shared memory
  interface to update the <b>EphemerisData</b> values.  It has the following 
  appearance.

  <p>
  <table cellpadding=10>
    <tr>
      <td> <img src=gui.jpg> </td>
      <td valign=top>
      Each of the text fields are a nifty FLTK Input_Valuator, which allow the
      user to either enter values directly from the keyboard, or click and 
      drag on the values to increment/decrement them.  Use of left, middle
      or right mouse button determine the step of incrementation.

      <p>
      Latitude can be set from -90 to 90.  Longitude can be set from -180.0 
      to 180.0.  The date can be set by selecting a choice of month, setting
      the day and year, or moving the horizontal scroll wheel just below the
      date to scroll through the dates of the year.

      <p>
      Likewise the time can be set by setting the hour, minute and second
      directly or moving the horizontal scroll wheel just below the time
      to scroll through the minutes of the day.

      <p>
      The <b>Now</b> toggle, when set, will simply update the time according
      to the current date and time as read from the computer's clock.  Dates
      and times cannot be changed while the <b>Now</b> toggle is set.

      </td>
    </tr>
  </table>

  <p>
  The GUI is compiled from the src/Gui directory, but leaves the executable
  in the bin directory.


<hr>
<table width=100%><tr>
    <td align=left><a href="updates_shmem.html">&lt;- Dynamic Updates using Shared Memory;</a></td>
    <td align=right> &nbsp; </td>
</tr></table>
</html>
